This invention relates generally to aerodynamic decelerators and more particularly to the aerodynamic stabilization of parachutes having square canopies.
When dropping a store such as a sonobuoy into the ocean from a high altitude it is necessary to assure proper orientation upon impact. This requires that the parachute used have both high drag to slow descent and stability to minimize store oscillations. Since stability decreases as drag is increased and vice versa, optimizing these two characteristics is most desirable. Cost and simplicity are also factors in designing a parachute and must be weighed against drag and stability.
Currently, aerodynamic decelerators such as crosstype parachutes require from 8 to 12 suspension lines to provide sufficient drag, which adds to cost and packing complexity and creates possible entaglement problems. Attempts to simplify parachute design have led to the use of parachutes with square canopies, which although simple, are inherently unstable. Stability has been improved by reducing the ratio of suspension line length to nominal canopy diameter, and by using different suspension line arrangements, such as suspension line shapers and/or criss-cross configurations. Although these modifications enhance stability, an even further enhancement thereof without further sacrifice in drag and/or simplicity is desirable.